Paint on stainless?

The factory painted them 40 plus years ago so there can't be a lot of science involved. They aren't 316 surgical stainless anyway. If the surface is scuffed to provide a tooth the paint should stick. Avery light coat ( just enough to cover ) is probably best. Sometimes a liquid mask works better than tape too.
i have covered a entire part with sheet material then cut out the detail with hobby knives.